Refusing the tadpoles is specifically opting out of the powers that they provide. It would make 0 sense to opt out of all these increases in power and then suddenly manifest the ability of flight out of nowhere.
At best, they could have a situation that enhances your original tadpole like Ormeluum's probing or the Zaithisk to grant flight... But it kind of defeats the whole "Lure of power" aspect of tadpoles if you get one of the stronger abilities irregardless of if you give in to ceremorphosis or not.
It doesn't have to come out of nowhere. I just think it's a shame that such a quality of life skill is gatekept behind this.
I'd rather they just debug the AI so companions follow you across gaps better.
Well, it would be great if they did that. But personally I'm not going to hold my breath.